This is a general outline; specifics may vary slightly based on your truck's exact configuration. Always consult a repair manual specific to your 1990 Chevy Scottsdale 1500 for detailed instructions and torque specifications.
Tools and Materials You'll Need:
* Repair Manual: Absolutely crucial for torque specs and step-by-step instructions.
* Jack and Jack Stands: Securely support the truck. Never work under a vehicle supported only by a jack.
* Wheel Chocks: For extra safety.
* Socket Set: Various sizes, including metric and standard.
* Wrench Set: Combination wrenches are helpful.
* Torque Wrench: Essential for proper tightening. Incorrect torque can damage the differential.
* Drain Pan: To catch the gear oil.
* New Differential Cover Gasket: Get the correct one for your differential.
* New Differential Cover Bolts (optional): It's a good idea to replace these if they're rusty or damaged.
* Gear Oil: The correct type and quantity specified in your repair manual.
* Gloves: To keep your hands clean.
* Cleaning Solvent: To clean the mating surfaces.
* Scraper: To remove old gasket material.
* Wire Brush: For cleaning the differential cover and housing.
* Safety Glasses: Protect your eyes.
Procedure (General Outline):
1. Safety First: Engage the parking brake, chock the wheels, and raise the rear of the truck securely with the jack and jack stands.
2. Drain the Gear Oil: Locate the drain plug on the differential housing. Place the drain pan underneath and carefully remove the plug. Let the oil drain completely.
3. Remove the Differential Cover: This usually involves removing several bolts around the perimeter of the cover. Keep track of their locations and order if necessary. You may need to use a breaker bar for stubborn bolts.
4. Clean the Surfaces: Carefully remove all traces of the old gasket from both the differential cover and the differential housing. Use a scraper, wire brush, and solvent to clean the surfaces thoroughly. Ensure both surfaces are clean, dry, and free of debris.
5. Install the New Gasket: Carefully apply the new gasket to the differential housing, ensuring it's seated properly.
6. Reinstall the Differential Cover: Align the differential cover and carefully bolt it in place, tightening the bolts in a star pattern (opposite bolts tightened in sequence) to ensure even pressure. Use your torque wrench and follow the torque specifications from your repair manual precisely.
7. Refill with Gear Oil: Consult your repair manual for the correct type and quantity of gear oil. Use a funnel to pour the oil into the differential.
8. Check the Oil Level: There's usually a fill plug (or sometimes a dipstick) on the differential housing. Add oil until it reaches the proper level.
9. Reinstall the Fill Plug (or Dipstick): Tighten to the manufacturer's specifications.
10. Lower the Truck: Carefully lower the truck using the jack.
11. Check for Leaks: After driving a short distance, check for any leaks around the differential cover.
Important Considerations:
* Torque Specifications: Using the wrong torque can strip threads or damage the differential. Always refer to your repair manual.
* Gear Oil Type: Use the correct type and weight of gear oil specified for your differential. Using the wrong oil can damage the gears.
* Threadlocker (Optional): Some mechanics use a small amount of threadlocker on the differential cover bolts to prevent leaks.
This is a general guide. A detailed repair manual specific to your vehicle is absolutely essential for a successful repair. Improper repair can lead to serious damage to your differential. If you have any doubts, consult a professional mechanic.
